Enter Load Details
Formula Used
General lighting load = floor area × 3 VA.
Small appliance load = effective small appliance circuits × 1,500 VA.
Laundry load = effective laundry circuits × 1,500 VA.
General demand = first 3,000 VA at 100%, next portion through 120,000 VA at 35%, and remaining portion at 25%.
Fixed appliance demand = fixed appliance VA × 75% when four or more eligible fixed appliances are entered. Otherwise, it uses 100%.
Continuous demand = continuous VA × 125%.
Motor addition = largest motor VA × 25%.
Final load = demanded general load + appliance loads + HVAC load + continuous demand + motor addition + spare capacity.
Calculated amps = final VA ÷ service voltage.
How To Use This Calculator
- Enter the dwelling floor area in square feet.
- Add the number of small appliance and laundry circuits.
- Enter appliance loads from nameplates whenever possible.
- Choose the cooking demand method that matches your review need.
- Enter heating and cooling loads separately.
- Select whether HVAC loads run together or separately.
- Add motor, continuous, EV, and spare capacity values.
- Press the calculate button and review the result above the form.
- Download the CSV or PDF file for records.
Example Data Table
| Example | Floor area | Fixed VA | Range VA | Dryer VA | HVAC used | Approx final load |
|---|---|---|---|---|---|---|
| Small dwelling | 1,200 sq ft | 4,000 VA | 8,000 VA | 5,000 VA | 7,000 VA | 31,370 VA |
| Medium dwelling | 2,000 sq ft | 6,000 VA | 12,000 VA | 5,000 VA | 10,000 VA | 45,625 VA |
| Large dwelling | 3,500 sq ft | 10,000 VA | 14,000 VA | 5,000 VA | 15,000 VA | 67,250 VA |
The example values are for demonstration only. Use actual nameplate values for real projects.
About This Load Calculator
This calculator gives a structured estimate for a standard dwelling electrical load. It is designed for planning, comparison, and early review. It does not replace an approved design. Local amendments, equipment listings, and field conditions can change the final answer. Save each result for comparison after every design change.
Why Demand Matters
A home has many connected loads. Yet every outlet, light, motor, heater, and appliance rarely runs at full output at the same moment. Demand factors reduce selected groups to a practical service load. This makes the result more realistic, while still keeping a safety focused method.
What The Tool Includes
The form includes floor area, small appliance circuits, laundry circuits, fixed appliances, cooking load, dryer load, water heating, EV charging, continuous loads, noncontinuous loads, HVAC, and largest motor load. It also adds spare capacity when requested. The result shows base volt amperes, demanded volt amperes, total service load, current, and a rounded service size.
Important Planning Notes
Use accurate nameplate values whenever possible. Do not guess large appliance loads. Enter heating and cooling separately. The calculator normally uses the larger HVAC value, because most homes do not run full heating and full cooling together. Choose simultaneous HVAC only when the design truly requires both loads at once.
Review Before Installation
This tool is useful for early budgeting and internal checking. It can help compare a 150 amp and 200 amp service. It can also show how an EV charger or electric range changes the total. Still, final service equipment, feeders, panels, grounding, conductor sizing, and permits should be reviewed by a qualified professional and the authority having jurisdiction.
Best Input Practices
Keep each value in volt amperes when the nameplate already lists VA. For watts, use the same number when power factor is not supplied. For kilowatts, multiply by one thousand. For amps, multiply amps by volts. Keep notes for any conversion. Clear notes make permit review easier.
Using The Results
The recommended service size is only a planning guide. It rounds the calculated amps to common service ratings. It does not verify panel spaces, breaker limits, feeder insulation, ambient correction, voltage drop, or utility rules. Always check the complete project before ordering equipment.
FAQs
What does this calculator estimate?
It estimates a dwelling service load in volt amperes and amps. It combines lighting, required circuits, appliances, HVAC, motors, and spare capacity.
Can this replace an electrician?
No. It is a planning aid only. Final sizing should be checked by a qualified professional and the authority having jurisdiction.
Why does the form use volt amperes?
Electrical service calculations commonly use volt amperes. If a device lists watts only, use that value when no power factor is supplied.
Why are two small appliance circuits used?
The calculator applies two as a minimum effective count. You can enter more circuits when the design includes them.
Why is one laundry circuit used?
The calculator applies one as a minimum effective count. Add more only when the dwelling design includes extra laundry circuits.
How is HVAC handled?
The default method uses the larger of heating or cooling. Choose simultaneous mode only when both loads can operate together by design.
What is spare capacity?
Spare capacity is an added planning margin. It helps compare future growth, but it is not a substitute for proper design review.
Why is the service size rounded?
The calculator rounds calculated amps to common service ratings. Actual equipment choices depend on local rules, utility limits, and product listings.